1. Field of the Invention
The invention relates to a process and device for the spinning of polyamides, like PA 6 and PA 6.6, comprising transporting vapor through at least one round spinning nozzle casing using an exhaust device positioned under at least one round spinning nozzle plate.
2. Summary of the Related Art
Processes and devices for transporting steam through spinning nozzle casings are known. Franz Fourne, Synthetische Fasern [Synthetic Fibers], Carl Hanser Verlag [Carl Hanser Publishing] Munich, Vienna 1995, pages 64, 348 and 362, states that it is advantageous to coat a spinning nozzle with steam that is generally superheated. This increases the cleanliness and usability of the undersides of the spinning nozzles by a factor of about two to four. Apparently, coating of spinning nozzles in this manner is particularly advantageous when spinning polyamide (PA) 6.6 fibers.
EP-B0 581 145 describes a process and device for manufacturing fibers that emit noxious gases and/or vapor during spinning. This process includes, among other features, a provision for removing the noxious gases and/or vapors produced during this process from the device and feeding them into a gas purification system.
It is known, according to Rogowin, Chemiefasem [Chemical Fibers], Georg Thieme Verlag [Georg Thieme Publishing] Stuttgart, New York, page 221, that the polymerization reaction of caprolactam is an equilibrium reaction and that the lactam remaining in the polymer, which boils at 258.degree. C., is very detrimental to spinning conditions. This is due to the fact that the lactam vapors can produce fiber breakage when they are released from the spinning nozzles together with the polymer melt. Similar disadvantages are also found in relation to the spinning of polyamide 6.6 fibers.
In addition, it is generally known that round spinning heads with round spinning nozzle plates can be used when spinning polyamide 6 or polyamide 6.6 fibers.